The initial description is quite similar to 1730, with the abandoned/long forgotten site theme.
The disc itself is the most interesting thing here, the idea of an anomaly that has been created specifically to expose the Foundation is good. I don't think "site is from a universe where the Foundation is destroyed" is a particularly interesting twist, however. There's a lot of articles and tales about the end of the foundation already, for example After The End.

The structure gets a little confusing later on in the article. It's a little unclear what's "our" Foundation and what's the other one. There are already test logs labelled A and B inside the Info Log, why are there then new test logs also labelled A and B after it? Which one is our Foundation and which is other?

"Designation" and "labelled" mean the same thing here so are kind of redundant. I'm also not convinced the Foundation would clearly label their secret facilities on the front door.

under its designation number

"Number" isn't needed, just "Under its designation".

along with any anomalous materials being housed in SCP-XXXX except 1

one, not 1.
Also, does this mean there is only one anomaly in the facility? I think this could be made clearer if that's the case, I read this as there are many materials but only one is recorded. Maybe replace "housed" with "contained"

has found one anomalous object which will be henceforth known as SCP-XXXX-1.

"one anomalous object, henceforth referred to as SCP-XXXX-1"

held in 3 x 3-meter case.

What do you mean case? 3 x 3 m is huge for a case, and later you say it's in a " 18.5 cm by 12.5 cm case".

from inside SCP-XXXX from the date █-██-████.

Maybe "from inside SCP-XXXX, all recorded on █-██-████". Avoids repetition of from.

If a Foundation staff member does view the contents of SCP-XXXX, they must be terminated immediately. See Addendum XXXXX.1

You refer to the disc as SCP-XXXX here and at a few other points in the article. This is SCP-XXXX-1.
Also why? I've seen Addendum XXXX-1, all it says is that information can't be removed by amnestics. Surely someone with high clearance knows the stuff it's saying anyway?

If a subject selected SCP Handling Training

The other paragraphs say "if the subject", this should be changed for consistency. Same with the next paragraph, which begins with "if a person"

SCP Handling Training

They don't call them "SCPs" in universe. I think "anomaly" is the go-to word here. SCP just stands for Special Containment Procedures.

If the class D was recently in contact with the SCP displayed on SCP-XXXXX-1 such as testing or anything else

"If the D-class recently interacted with the anomaly on display they will"
No need for " such as testing or anything else" and I personally think D-class looks better than class D.

disk.SCP-XXXXX-1

needs a space

homocidal tendencies

homicidal

and will continue to increase in frustration.

"and frustration will continue to increase"

The civilian then attacked said field agent without being provoked in any way. The civilian also appeared to know that the field agent was under the employment of the Foundation while directing insults at the Foundation and appeared to show hostility to the activities of the Foundation.

Most of this just repeats the line above it. I think "The civilian was aware of the agent's position within the Foundation and expressed anti-Foundation sentiment" gets the point across quicker.

this included name calling and derogatory speech directed at Foundation procedures

This doesn't seem like extreme hostility. Extreme would be them actively attacking MTF members, rioting, etc

Protocol 12 was enacted to ███ people

This word can only be "kill", right? Or "terminate"? Why censor it?

someone had just donated the disk to my store without needing any payment for it.

"someone donated the disk to my store for free", "without needing any payment" is quite wordy.

Foundation closed the video store permanently

You've already said this.

which described the people affected by SCP-XXXXX-1 as a mob of people with sadistic views.

This is awkward phrasing. I think "a cult" might work better.

News of the incident regarding SCP-XXXXX-1's containment went unnoticed by the public along with the field agent being removed and transferred to another site.

I think this whole sentence is unnecessary.

due to the importance of containment of important information vital to the Foundation.

Lot's of important in this sentence, it's a little redundant.

while a Foundation staff member was doing drone testing

Just "during testing"

This information infers

infer is something you do with the information, not the information. The information implies (or outright states).

being sold by a third party to numerous GoIs, many of which have been unknown to the Foundation

How do they know this just from number of copies sold?

However, no GoIs have attacked the Foundation thus far with knowledge towards SCP-XXXXX.

Who took the time to cross this out during the GoI invasion/mass collapse of the Foundation?

I don't think any of the test logs are necessary. They all just rehash information we already know and crosslink to other SCPs for no real reason. They don't add anything to the article, I don't think they're needed.

There's so much censored information in the event description that it becomes very jarring to read. I think this event adds an unnecessary danger onto the end of the article, I think the narrative would be better if it ended with the "almost exposure" when the disc was first discovered. This event log is a little bland.